In a photoresist process which is one type of semiconductor manufacturing processes, a spin coating apparatus for supplying a coating liquid such as a resist or the like onto a surface of a semiconductor wafer (hereinafter, referred to as a wafer) and coating the entire surface of the wafer with the coating liquid while rotating the wafer, has been used. In such a coating processing apparatus, a cup body is installed to surround a wafer held by a spin chuck and to accommodate a coating liquid scattering from the wafer. In addition, an annular exhaust path is formed along a circumferential direction of the cup body, and an ambient atmosphere of the wafer is exhausted via the exhaust path.
In recent years, with the high integration of semiconductor circuits, devices with a more complicated three-dimensional structure have been studied. In a case of manufacturing such devices, from the viewpoint of increasing an etching resistance, there is a demand to make a resist film thick and there is also a need to use a resist liquid having high viscosity of 200 cP or more. When a material having high viscosity is coated by spin coating, a coating liquid dropped from the periphery of a wafer when the coating liquid coated on the wafer is diffused may be deformed to have a string shape. When such a string-shaped coating liquid clogs an exhaust path, there is a problem that an exhaust pressure decreases. As such, there is a need to periodically perform maintenance to remove the string-shaped coating liquid.
As measures against such a string-shaped coating liquid, for example, a configuration has been used in which an annular coating liquid collecting member for collecting the string-shaped coating liquid is installed in an annular exhaust path formed to surround a wafer. By installing such a coating liquid collecting member, it is possible to collect a coating liquid tending to flow into, for example, an exhaust duct located at a downstream side of a cup body. However, such a configuration requires removing the string-shaped coating liquid collected in the coating liquid collecting member.
In some configurations, a rinse is used to clean a rear surface of a wafer, and a coating liquid collecting member is cleaned using the rinse dropped from the wafer. Moreover, the rotation speed of a wafer varies or fluctuates depending on a process recipe of the wafer. This makes it difficult to stably supply a liquid toward the coating liquid collecting member during wafer processing. Therefore, in addition to the process of processing the wafer, it is necessary to supply the rinse toward the coating liquid collecting member to clean the coating liquid collecting member, which results in poor throughput.
In addition, a technique for discharging and removing a solvent toward a string-shaped (thread-shaped) coating liquid generated at the periphery of a rotating wafer has been used. However, the string-shaped coating liquid is easy to scatter, which makes it difficult to reduce an amount of coating liquid captured by an exhaust stream at a suitable level. Further, it is necessary to continue supplying the solvent during a resist coating process. This may increase an amount of chemical solution used.